Effect of formation strength anisotropy on wellbore shear failure in bedding shale

Cao, Wenke; Liu, Wei; Liu, Hailong; Lin, Haifei

doi:10.1016/j.petrol.2021.109183

Cited by 8 publications

(2 citation statements)

References 32 publications

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“…Shale gas, classified as an unconventional energy source [6][7][8], exhibits tremendous potential as a feasible substitute for traditional oil and gas resources. As a result, it has attracted considerable interest from scholars both domestically and internationally [9][10][11][12]. China possesses abundant supplies of shale gas, and many other nations have intensified their research on and use of shale gas in recent years [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Characterization of the Fine-Scale Evolution of Damage in Shale under the Influence of Two-Way Stress Differences Based on CT Images and Fractal Theory—The Example of the Anba Dyke in the Wufeng–Longmaxi Formation

Lan,

Yang,

et al. 2024

Fractal Fract

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To better understand the influence of different levels of two-way stress differences on the development of damage in Anchang diametral laminar shale in the northern Qianbei area, a numerical model of laminar shale with a representative fine-scale structure was established by using RFPA3D-CT. A triaxial compression test was conducted; a three-dimensional mesoscale fracture box dimension algorithm based on digital images was generated by using MATLAB R2020b; and the fractal characteristics were quantitatively analyzed. The results showed that under the influence of the horizontal stress ratio and two-way stress, the greater the two-way stress is, the more notable the plastic characteristics of specimen damage are, and the higher the residual strength is. The specimens with lower two-way stress exhibited obvious brittle damage characteristics. The difficulty degree of complex fracture network formation increased with the increase in the horizontal tension ratio, and the degree of increase in the fracture network complexity gradually decreased. At a horizontal stress ratio of 1.25, the fractal dimension was the highest, which indicates that the cracks were the most pronounced. Fracture formation after specimen damage was the most common phenomenon. Under the condition of a lower horizontal stress ratio, a large number of fracture structures could be generated in shale specimens after damage, promoting the expansion of natural fractures.

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Section: Introductionmentioning

confidence: 99%

Characterization of the Fine-Scale Evolution of Damage in Shale under the Influence of Two-Way Stress Differences Based on CT Images and Fractal Theory—The Example of the Anba Dyke in the Wufeng–Longmaxi Formation

Lan,

Yang,

et al. 2024

Fractal Fract

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“…However, shale, as one of the most widespread sedimentary formations on Earth, exposed well-defined anisotropy in the form of bedding, lamination, foliation (repetitive layering), fissuring, or jointing. , The fissures or joints could generate anisotropic and preferential fluid flow paths , and lead to a certain level of discontinuity, depending on the size of the problem of interest . For example, for a regional problem on the reservoir scale, the associated deformation discontinuity across enormous fissures and joints could be ignored, while they mostly contribute to the fluid flow through the so-called multiple porosity model. ,– Therefore, in this study, we focus on the so-called intact anisotropy, which means that for any material point in the domain, the stiffness and/or permeability vary with the observing direction. ,, This anisotropy can have a significant impact on the way that fractures propagate through the rock, , the direction in which gas flows, , and the shear failure. – Therefore, coupled hydro-mechanical simulations should take the anisotropic characteristics into account. ,– …”

Section: Introductionmentioning

confidence: 99%

Material Constants of Anisotropic Poroelasticity and Its Impacts on Shale Gas Production

Zhang,

Yin,

Yan

2023

Energy Fuels

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While the production of shale gas is always accompanied by stratum deformation, previous studies have commonly assumed isotropy to simplify the modeling process despite substantial experimental evidence supporting the anisotropy of these formations. This work contributes to both theoretical and practical aspects of anisotropy. For the theoretical aspect, a novel mixture theory approach is used to explore the poromechanical constants of anisotropic poroelasticity. By incorporating new elements in the modeling of intrinsic solid density and unjacketed frame deformation, we are able to establish a complete set of parameters considering micro-inhomogeneity and micro-anisotropy in a macroscopically anisotropic porous medium like shale. The bounds on the material constants are established, and their relationship with the intrinsic material constants of poroelasticity proposed by Cheng ( 2021) is discussed. In a practical context, we examine the impacts of anisotropy in a 3D shale gas reservoir considering both elastic and permeability anisotropy. For elastic anisotropy, compared with the isotropic counterpart, we identify significant dissimilarities in the horizontal stress parallel to the wellbore (σ xx here) between assumptions of isotropy and transverse isotropy. For permeability anisotropy with an inclined plane of isotropy, the gas production is largely inhibited, and we could observe the stress distribution reorientation. To conclude, isotropic models are unable to reproduce the stress changes predicted by the anisotropic models, and this research contributes to a better understanding of anisotropy in shale gas reservoirs.

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A Novel Semi-analytical Model to Predict Elastic Compliance Around the Cased Borehole

et al. 2022

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Effect of formation strength anisotropy on wellbore shear failure in bedding shale

Cited by 8 publications

References 32 publications

Characterization of the Fine-Scale Evolution of Damage in Shale under the Influence of Two-Way Stress Differences Based on CT Images and Fractal Theory—The Example of the Anba Dyke in the Wufeng–Longmaxi Formation

Characterization of the Fine-Scale Evolution of Damage in Shale under the Influence of Two-Way Stress Differences Based on CT Images and Fractal Theory—The Example of the Anba Dyke in the Wufeng–Longmaxi Formation

Material Constants of Anisotropic Poroelasticity and Its Impacts on Shale Gas Production

A Novel Semi-analytical Model to Predict Elastic Compliance Around the Cased Borehole

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